As well as finishing with a team-high 26 points, Dieng grabbed a tournament-high 15 rebounds and dished out three assists in 35 minutes on floor.
It was the most contest game of the tournament so far, as Morocco fought back to every Senegal’s attempt to move away.
Morocco, paced by an electrifying Abdelhakim Zouita, led by as many as five minutes in the second quarter.
But when Dieng, who had only five points in the first-half, stepped up Senegal seemed destined to win the contest.
A frontrunner in the tournament, Senegal needed to open the tournament with a win.
Both Maleye Ndoye and Antoine Mendy contributed 17 points apiece for Senegal in a game that registered six lead changes.
Zouita was for Morocco as Dieng was for Senegal.
The versatile Moroccan forward, who led all scorer with 27 points, put on a show destroying Senegal’s defense with dunks after dunks as Mustapha Khalfi and Soufiane Kourodou contributed 12 points apiece for the North African side.
Eventually it was Senegal who celebrated last.
In the early game of Group B action, Angola survived a Mozambique scare after trailing 43-32 at the break.
Carlos Morais, who was named the tournament MVP a couple of years ago, carried the AfroBasket reigning champions to a 84-72 victory.
He had a team-high 18 points, but Mozambique point guard Augusto Mayos grabbed the limelight with a game-high 25 points.
Early in the day, Cape Verde trounced Ivory Coast 76-56, while Algeria easy past AfroBasket debutant Zimbabwe 87-67.
AfroBasket 2015 resumes on Friday with hosts Tunisia taking on the Central African Republic, Gabon will go against Mali.
In the highly anticipated of Group C, Egypt will square off against Cameroon and Al-Farouq Aminu’s Nigeria will take on Uganda.